Many types of devices and systems use power supplies that are stacked or coupled in series. For example, electric vehicles often include multiple lithium batteries or other batteries arranged in stacks. Each battery is typically designed to provide a specified voltage (such as approximately 5V) up to a maximum voltage (such as approximately 5.5V). In a twelve-battery stack, the stack could be designed to provide a voltage of approximately 60V. It may be necessary or desirable to measure the voltage across individual batteries in the stack. This could be useful, for example, to control the charging or discharging of individual batteries in the stack. However, batteries near the “top” of the stack may be at significantly higher voltages (such as approximately 45V-55V), which makes it difficult to measure the voltage across those batteries.